Topic: Help me pick a chain and sprocket set for my F2

[MOONDOGNYC]

 Reading through an hours worth of posts and i think I am more confused now, than when I started. 
 I have a '77 CB750F2 and am very skeptical about my current chain and sprockets. I have read that the stock setup was 14-43 with a 630 chain. I have also read that a good setup would be to go with 17-48 and a 530 chain.
  I have no idea how the gear ratios equal each other, nor do I know if I should stick with a stock type setup...the stock sprockets and chain replacements are also a little tough to find.
   Can anyone explain this?  ...appreciate it.

[scottly]

To find the ratio, divide the number of teeth on the rear sprocket by the number of teeth on the front sprocket. A higher number ratio will produce more acceleration, at the cost of higher RPM at the same speed. Ironically, higher numbered ratios are referred to as "lower" gearing. I believe the late F had 15/43?
14/43= 3.07
15/43= 2.866
15/41= 2.733 (stock K7 gearing)
16/48= 3.00
17/48= 2.823
18/48= 2.66

[TwoTired]

The CB750 shop manual supplement 25, lists 3.071 as the final drive ratio for the F2.  Recall the F model had a higher red line than the rest of the models.

There is a notation written in my book that the sprockets were 14 T front and 43T rear for the 630 chain on the F2.

The primary and trans ratios were the same for the K7 and F2.  FYI

The 530 ratios would use a 48T rear sprocket.  But, note that you will need 530 sprockets front and rear to go with a 530 chain. 
If you wanted a similar ratio as what the bike had stock, and desired a 530 set up, then a 16/48 would be pretty close.

However, a 14/43 with 630 oring chain combo will likely be the last chain you ever install on the bike, assuming correct routine maintenance, of course.   Just make sure that battery acid cannot ever get to the chain (reroute battery overflow tube).

[brandEn]

I run 17/48 with a 530 chain on my 78F and love the ratio.

Do you have the stock 630 chain?

[scottly]

The CB750 shop manual supplement 25, lists 3.071 as the final drive ratio for the F2.  Recall the F model had a higher red line than the rest of the models.

There is a notation written in my book that the sprockets were 14 T front and 43T rear for the 630 chain on the F2.

I stand corrected.  

[MOONDOGNYC]

Thank you all !!

TOA.. I do have the original on the bike.

My last question is, why/what is the difference between 630 and 530 chains ? Bigger ? Why ? ...sorry to be a pain, but I just want to be positive before I spend more cash. (I have spent a bit already   ).

[2wheels]

I have an F3 that I changed to the K ratio.  That is 630 chain, 15 front and 41 rear.
It is a good ratio for the mostly highway driving I do.

The 630 chain did not have to be adjusted as often.  I think that is why Honda changed.

I just put a new DID O ring chain on 2 weeks ago.  Yesterday I took the engine cover off and I see the chain has hit the cover a couple times.  The chain is not hitting the engine cases though.

I wish I would have changed over to the 530 chain.  It is lighter.

[Schnell]

Moondog, 530 chain is thinner and lighter than 630 chain. 630 chain is overkill on these bikes. Most sport bikes today, which are more powerful than our vintage bikes, use chain lighter than 630. Perhaps some of the big cruisers use heavier chain.

If you switch the chain size from 630 to 530 on your bike, you will need to buy new 530 sized sprockets to match.

From experience, having recently replaced the worn 530 chain on my bike, if you spend more to get an o ring chain, you will need to have a $80 master link chain tool. If you buy regular non o ring chain, it is less expensive by half, and can be connected using a clip style master link, no need for the chain tool.

[2wheels]

schnell
can you explain the master link tool.  I just put on an O ring chain and it was hard to put the master link on.  The O rings need to be compressed.

[Schnell]

It's a clamp type affair with a big screw, to push the side plate on, and then to mushroom the end of the master link pins so the side plate can not come off.

YouTube has instructional videos.

[seanbarney41]

I have been running clip type master links on o-ring chains for years...you just always have to buy the clip type master link separately,  o-ring chains always come with the master link that requires the chain tool

[Schnell]

Okay, good to know. I was told false info by the DT Power Sports dealer local to me.

My other older bikes are both shaft drive, so my knowledge and experience with chain drive is thin. Learning as I go.

[TwoTired]

My last question is, why/what is the difference between 630 and 530 chains ? Bigger ? Why ? ...sorry to be a pain, but I just want to be positive before I spend more cash. (I have spent a bit already   ).

The 750 Honda had a reputation with 530 chains breaking and putting a hole in the lower engine case.  As to why, the speculation in the consumer community was that the 530 chain was too weak for the power of the bike.  To aleve buyer fears, Honda put the stronger 630 O ring chain on the 750s for the 1977 model year with these model engines producing more power than earlier models.

I don't think earlier models had stock oring chains.  So, this was probably a compensation for owners who generally ignored chain maintenance, and blamed the chain for breakage, rather than the improper treatment of the chain.
There was also some dealer notification to inspect and correct any battery drain tube routing problems that would allow battery acid to drip on and weaken chains.

The 630 tooth spacing is 6/8 of an inch.  The 530 tooth spacing is 5/8 of an inch.  So, sprockets and chains are not interchangeable amoung the different types.

While the 630 chain is likely overkill and certainly heavier than a 530 for the 750,  the warranty claims for holed cases due to chain breakage was pretty much eliminated for the new models.

So, it's rather the classic speed vs durability trade off, and the o ring type generally needs less prompt attention for maintenance than a 530 non oring, which is considerably lighter.

The choice depends on the purpose of the bike,  If you are desperate to keep up with modern sport bike, the lighter chain will help.  If you want minimal attention placed upon the chain, for the rest of you time in ownership, stick with the 630.  There are, of course, choices in between that may be better for your goals.

But, you haven't told us what you want, besides inexpensive.  Toward that end, there are short term expenses vs long term expenses.  The 630 may be less expensive in the long term, even if pricey to install now.  If immediate wallet relief is essential, clearly 530 sprockets and standard 530 chain will have you rolling now at minimum cost.  But, you can expect to replace all the components earlier than the 630 set up, particularly if you lapse with chain maintenance.

I need to ask. Are your current chain and sprockets really worn out?  Or, do you just suspect that?  Have you measured wear?  Can you see damage?

[MOONDOGNYC]

I have not measured the sprockets in question, but the chain is definitely gone. Binding in spots and rusty. Because of that, coupled with reading that the 17-48 with a 530 is the way to go, I was deciding to replace the 630 chain and sprockets to 530...just wanted to know why I was choosing that setup...lol

[TwoTired]

I have not measured the sprockets in question, but the chain is definitely gone. Binding in spots and rusty. Because of that, coupled with reading that the 17-48 with a 530 is the way to go, I was deciding to replace the 630 chain and sprockets to 530...just wanted to know why I was choosing that setup...lol

Ok, I won't bother you with information, anymore.

[MOONDOGNYC]

Hahhaaa...bother away !!  (THANK YOU BIG TIME) The info you provided was spot on. Helps my decision making for sure.
  Even though this is my first CB750, I know from experience (albeit different bikes), that buying a part/parts can sometimes be a repetitive experience, once you find the correct/nicer part.
  Thanks all for the feedback and edification.